JP2024516959A - Magnetic shield structure for wireless charging and manufacturing method thereof - Google Patents

Abstract

[Problem] The present invention discloses a magnetic shield structure for wireless charging and a manufacturing method thereof, which belongs to the technical field of wireless charging. [Means] The magnetic shield structure includes a plurality of nanocrystal units and a heat conduction unit. The heat conduction unit is provided between the nanocrystal units and is used for connecting each nanocrystal unit and for heat conduction. The nanocrystal unit includes multiple layers of nanocrystal material. The application provides a magnetic shield structure and a manufacturing method thereof that has low eddy current loss, good heat dissipation, good insulation performance, good flexibility, high reliability, small volume, light weight, and is applicable to high-power wireless charging. [Selected Figure] Figure 1

Description

The embodiments of the present application relate to the technical field of wireless charging, for example, to a magnetic shield structure for wireless charging and a manufacturing method thereof.

With the rapid development of the electric vehicle industry, wireless charging of automobiles has attracted more and more attention. Compared with wired charging technology, wireless charging is smarter, safer and more convenient. Compared with wireless charging of consumer electronic products (e.g., mobile phones), wireless charging of electric vehicles requires a higher system power, generally above 6kW, and the system is more complex and technically difficult. Magnetic materials are an important component of high-power wireless charging systems, mainly playing the role of magnetic conduction and magnetic shielding. High-performance magnetic materials can greatly improve the coupling coefficient of the charging system and further improve the charging efficiency, while effectively shielding the leakage of electromagnetic fields and avoiding interference or damage to the external environment.

At present, the magnetic material used in the receiving end of the high-power wireless charging system is mainly soft magnetic ferrite material, which has high magnetic permeability and resistivity, good magnetic isolation effect, and low eddy current loss. However, ferrite material has obvious defects such as low saturation magnetization strength (generally less than 0.5 T), brittleness, and fragility. The low saturation magnetization strength increases the volume and weight of the material, which is disadvantageous for miniaturization of the element. At the same time, the size of the ferrite magnetic plate is usually limited due to the manufacturing process. Therefore, the magnetic plate for the high-power wireless charging receiving end is made of multiple ferrite magnetic plates joined together, and combined with the brittleness of ferrite itself, it is easily shattered during the driving process of the car, which greatly reduces the reliability of the system.

Compared with soft magnetic ferrite materials, nanocrystalline materials have higher saturation magnetization strength, which is more than twice that of ferrite materials. At the same time, flexible magnetic sheets can be manufactured in the form of split, viscose, etc., to avoid defects that are easily broken. However, due to defects such as low resistivity of nanocrystalline materials, when the materials are used at high frequencies, obvious vortexes are generated and losses are large. In particular, for high-power wireless charging systems, the strong vortex effect and high losses cause a large amount of heat energy to be generated and cannot be dissipated immediately, which ultimately reduces the charging efficiency and safety of the system. By performing split and film attachment processing on nanocrystalline materials, the frequency of use of nanocrystalline materials can be improved to a certain extent and vortex losses can be reduced, but for high-power wireless charging systems, the vortex losses and heat problems are still serious. This is mainly because several microcracks are formed on the surface of the nanocrystalline after splitting. That is, multiple chopped units (submicron order) with non-uniform size and shape are formed on the surface of the nanocrystalline strip, and obvious magnetic field accumulation phenomenon occurs at the corners of the chopped units, resulting in large losses and severe heat generation during the work process. At the same time, after the film attachment process, the polymer material in the adhesive layer cannot effectively penetrate into the microcracks, and the insulation effect is greatly reduced. In addition, the adhesive used in the film attachment process has poor thermal conductivity, so the heat caused by eddy current loss cannot be effectively and quickly dissipated.

Therefore, the prior art still needs to be improved and developed.

The following is a general overview of the subject matter described in detail herein, and is not intended to limit the scope of the claims.
The embodiments of the present application provide a magnetic shield structure for wireless charging, which has low eddy current loss, good heat dissipation, good insulation performance, good flexibility, high reliability, small volume, and light weight, and a manufacturing method thereof.

A magnetic shield structure for wireless charging, comprising a plurality of nanocrystal units and a heat conduction unit,
the thermal conduction units are provided between the nanocrystal units and are used for connecting the nanocrystal units and for thermal conduction;
The nanocrystalline unit includes multiple layers of nanocrystalline material.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The material of the heat-conducting unit includes a heat-conducting potting agent and an epoxy resin.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The thermal conductive potting agent is made of silica gel material;
The epoxy resin used is one modified with a polyamide resin.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The mass ratio of the thermally conductive potting agent to the epoxy resin is 1:1 to 5:1.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The layers of nanocrystalline material are adhered together by an adhesive layer.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
the nanocrystal units are rectangular;
the plurality of nanocrystal units are in a matrix distribution;
The magnetic shield structure formed is rectangular.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The nanocrystal units have a side length of 5-15 mm and a thickness of 1-10 mm.

As a preferred embodiment of the above-mentioned magnetic shield structure for wireless charging,
The nanocrystal units have a thickness of the nanocrystal material of each layer of 14 to 20 microns, and the distance between adjacent nanocrystal units is 0.1 to 0.5 mm.

The manufacturing method used for the above-mentioned magnetic shield structure for wireless charging includes the following steps:
(1) the nanocrystal strip is sequentially double-sided-film-applied and split, and then multiple layers of the nanocrystal strip are adhered and laminated through adhesive layers to reach a desired thickness h;
(2) cutting the composite material of the multiple layers of nanocrystal strips and adhesive layers produced in step (1) into multiple rectangular nanocrystal units with square top faces;
A step (3) of arranging and fixing the plurality of nanocrystal units produced in the step (2) on a mold or a flat plate so that the distance between adjacent nanocrystal units is b;
(4) mixing and stirring the thermally conductive potting agent and the epoxy resin according to the ratio to obtain a colloid for forming a thermally conductive unit;
Step (5) of filling the gaps between the nanocrystal units in step (3) with the colloid of heat conduction units produced in step (4) to form a semi-finished magnetic shield structure;
and (6) hardening the semi-finished magnetic shield structure manufactured in the step (5) to obtain a finished magnetic shield structure.

The beneficial effects of the present application are as follows: The magnetic shield structure is composed of a plurality of nanocrystalline units. The nanocrystalline units are provided with thermally conductive units. The material of the thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive unit connects the nanocrystalline units while also playing the role of thermal conduction and heat dissipation, so that the magnetic shield structure of the present application has good heat dissipation performance and is applicable to high-power wireless charging. The magnetic shield structure of the present application composed of a plurality of nanocrystalline units has higher charging efficiency, lower heat dissipation, and higher reliability than the magnetic shield structure using only nanocrystalline strips as the magnetic shield material. When the nanocrystalline units are embedded in the thermally conductive material, the nanocrystalline units are smaller than the size of the long nanocrystalline strips, which greatly reduces the eddy current loss, while the thermal conductive material is introduced to increase the thermal conductivity properties of the magnetic shield structure, and the heat caused by the eddy current loss can be dissipated quickly.

Other aspects can be understood after reading and understanding the drawings and detailed description.

The drawings are intended to provide a further understanding of the technical solutions of this specification, constitute a part of the specification, and are used to interpret the technical solutions of this specification together with the examples of this application, and are not intended to limit the technical solutions of this specification.

FIG. 2 is a schematic front view of a magnetic shield structure for wireless charging in an embodiment of the present application. FIG. 2 is a schematic perspective view of a magnetic shield structure for wireless charging according to an embodiment of the present application. FIG. 2 is a comparative diagram of test results of Example 1 and Comparative Examples 1 to 3 in the present application. FIG. 2 is a comparative diagram of test results of Example 2 and Comparative Examples 4 and 5 in the present application. FIG. 2 is a comparative diagram of test results of Example 3 and Comparative Examples 6 and 7 in the present application. FIG. 1 is a comparative diagram of test results of Example 4 and Comparative Examples 8 to 9 in the present application. FIG. 1 is a comparative diagram of test results of Example 5 and Comparative Examples 10 to 13 in the present application. FIG. 1 is a comparative diagram of test results of Example 6 and Comparative Examples 14 to 15 in the present application.

The present application will be described in more detail below with reference to the drawings and examples. It should be understood that the specific examples described in this specification are merely for the purpose of interpreting the present application and do not limit the present application. For ease of explanation, the drawings show only some of the structures related to the present application, but not all of them.

In the description of this embodiment, the orientations and positional relationships of the terms "up," "down," "left," "right," and the like are based on the orientations and positional relationships shown in the drawings, and are merely for the purpose of facilitating the description and simplifying the operation, and should not be understood as indicating or implying that the mentioned devices or elements have a specific orientation, or must be constructed and operated from a specific orientation. Therefore, it should be understood that they do not limit the present application.

The technical solution of this application will be further explained below with reference to specific embodiments in conjunction with the drawings.

The embodiment of the present application provides a magnetic shield structure for wireless charging. FIG. 1 is a front view structural schematic diagram of the magnetic shield structure for wireless charging in the present application. As shown in FIG. 1, the entire magnetic shield structure includes a plurality of nanocrystal units 1 and a heat conduction unit 2. The heat conduction unit is provided between the nanocrystal units. The heat conduction unit is used to connect each nanocrystal unit, while enabling heat conduction and heat dissipation, so that the magnetic shield structure according to the present application has good heat dissipation performance, and is particularly applicable to high-power wireless charging. The nanocrystal unit includes multiple layers of nanocrystal material. The multiple layers of nanocrystal material are stacked in order to form the nanocrystal unit. The nanocrystal material is mainly used to provide magnetism and plays the role of magnetic isolation and shielding. The multiple layers of nanocrystal material are bonded together by an adhesive layer. The adhesive layer plays the role of bonding the nanocrystal material and the role of insulation. FIG. 2 is a perspective structural schematic diagram of the magnetic shield structure for wireless charging in the present application. As shown in FIG. 2, the nanocrystalline unit includes multiple layers of nanocrystalline material, which means that the nanocrystalline material is stacked in the thickness direction h of the magnetic shield structure to form a nanocrystalline unit with a certain thickness h. Adjacent nanocrystalline material layers are bonded to each other by an adhesive layer.

In one embodiment of the present application, although there is no limitation on the nanocrystalline alloy system and components, since it is necessary to have good soft magnetic properties, Fe-Si-Nb-B-Cu system is preferred. The nanocrystalline material has a real permeability in the range of 600 to 15,000 at an operating frequency of 100 kHz. The thickness of one layer of nanocrystalline material is 14 to 20 microns, and the thickness of the adhesive layer is 5 to 12 microns, preferably 5 to 8 microns. In connection with Figures 1 and 2, as shown in Figure 1, the nanocrystalline unit has a square front. The multiple nanocrystalline units are distributed in a matrix, and the front of the formed magnetic shield structure is also square. Referring to Figure 2, the nanocrystalline unit has a certain thickness h, so that the entire nanocrystalline unit has a rectangular parallelepiped shape with a square front. The size of the side length a of the front of the nanocrystalline unit is 5 to 15 mm. If the size of the side length a is too large, it will greatly increase the eddy current loss, causing the system to generate excessive heat; if the size of the side length a is too small, it will cause the nanocrystal units to be isolated and dispersed by the heat conduction units. That is, by increasing the air gap, the permeability of the entire magnetic shield structure will obviously decrease, further affecting the coupling coefficient and wireless charging efficiency of the system. At the same time, the introduction of a large amount of air gap will reduce the eddy current loss to a certain extent, but will increase the hysteresis loss. The thickness h of the magnetic shield structure, which is the thickness h of the nanocrystal units, is 1-10 mm, and preferably 2-5 mm.

The thermally conductive unit is made by mixing a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent mainly plays the role of thermal conduction and insulation. The epoxy resin mainly plays the role of adhesion, and can improve the adhesive strength of the nanocrystal unit. The cured thermally conductive potting agent has a good thermal conductivity coefficient, adhesiveness and flexibility. The thermally conductive potting agent is preferably a silica gel material. The epoxy resin includes an epoxy resin and a modified epoxy resin. Since the epoxy resin is required to have good adhesiveness and a certain degree of flexibility after curing, it is preferably an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is (1:1) to (5:1). The thermally conductive units are distributed among the nanocrystal units. In this application, as shown in FIG. 2, the size of the width b of the thermally conductive unit, which is the distance b between adjacent nanocrystal units 1, is 0.1 to 0.5 mm, and preferably 0.1 to 0.3 mm. If the value of b is too large, the ratio of the magnetic phase in the entire magnetic shield structure can be reduced by increasing the distance between the nanocrystal units. In this application, the thermal conduction unit has excellent flexibility and adhesion, which prevents the nanocrystalline material from falling off or breaking during the work process, greatly improving the reliability of the system.

Compared with conventional ferrite magnetic shielding structures, the magnetic shielding structure based on nanocrystals according to the present application is lighter in weight, smaller in volume, more reliable, and has a slightly higher charging efficiency. A high-power wireless charging system based on the magnetic shielding structure according to the present application is more efficient, generates less heat, and is more reliable than a system that uses only nanocrystal strips as the magnetic shielding material. When the nanocrystal units are embedded in the thermally conductive material, the nanocrystal units are smaller in size than the long nanocrystal strips, greatly reducing eddy current losses, while the introduction of the thermally conductive material increases the thermal conductivity properties of the magnetic shielding structure, allowing the heat caused by eddy current losses to be dissipated quickly.

The embodiment of the present application further provides a manufacturing method for manufacturing the above magnetic shield structure, including the following steps:

(1) After the tempered nanocrystalline strip is double-sided filmed and split, multiple layers of the nanocrystalline strip are adhered and laminated via adhesive layers to reach the expected thickness h.

The purpose of the splitting process is to chop the nanocrystalline strip and further improve the high frequency characteristics of the nanocrystalline strip while adjusting the real permeability of the nanocrystalline strip based on the split shape and its strength. The split shape is not limited, and double roll crimping is preferred.

(2) The composite material of the multiple layers of nanocrystal strips and adhesive layers produced in step (1) is cut into multiple rectangular nanocrystal units with square top faces, i.e., multiple a x a x h rectangular parallelepipeds, to obtain nanocrystal units. The cutting form is not limited and includes, but is not limited to, wire cutting, laser cutting, die cutting, etc.

(3) The nanocrystal units produced in step (2) are arranged and fixed in a mold and/or a flat plate, ensuring that the distance between adjacent nanocrystal units is b.

(4) Mix and stir the thermally conductive potting agent and epoxy resin in the appropriate ratio to obtain a homogeneously mixed colloid for forming the thermally conductive unit.

(5) The thermal conduction unit colloid produced in step (4) is filled into the gaps between the nanocrystal units in step (3) to form a magnetic shield structure semi-finished product. It is required that the thermal conduction unit colloid completely enters the gaps between the nanocrystal units, adheres well to the cross-sections of the nanocrystal units, and has no obvious bubbles in the colloid. The filling form is not limited, and includes, but is not limited to, injection, dispensing, impregnation, etc., and a pressurized impregnation form, i.e., impregnation when a certain pressure is applied, is preferred.

(6) The magnetic shield structure semi-finished product manufactured in step (5) is hardened to obtain a finished magnetic shield structure. The hardening conditions are not limited, but hardening at room temperature or low temperature is preferable. The hardening temperature does not exceed 80°C, and a magnetic shield structure for high-power wireless charging is finally obtained.

[Example 1]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conductive unit (thermal conductive adhesive).

The nanocrystalline unit was composited with 120 layers _of nanocrystalline material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The _{nanocrystalline} material has a real permeability of 10354 in the operating mode with an operating frequency of 100 _kHz . The average thickness of the nanocrystalline material is 19 microns, and the thickness of the adhesive layer is 6 microns. The nanocrystalline unit is shaped like a rectangular parallelepiped, of which the surface shape is a square, and the size of the side length a is 10 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 2:1. The size b, which is the distance between adjacent nanocrystal units, is 0.2 mm.

The magnetic shield structure consisting of the nanocrystal unit and the thermal conduction unit has a size h of 3 mm in the thickness direction, and the length x width x thickness of the magnetic shield structure is 420 mm x 420 mm x 3 mm.

test:

First, a test was performed on the magnetic permeability of the nanocrystalline strip for subsequent calculations. The nanocrystalline strip is the nanocrystalline strip in step (1) above. The nanocrystalline strip was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm, and a magnetic permeability test was performed. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 1]
As a comparative example of Example 1, the wireless charging magnetic shield structure was joined by 16 square ferrites. The material of the ferrite was manganese zinc ferrite, and the model number was PC95. The size of each square ferrite was 105 mm x 105 mm x 3 mm. The square ferrites were directly bonded and connected with epoxy resin.

[Comparative Example 2]
As a comparative example of Example 1, a wireless charging magnetic shield structure was bonded with 16 square ferrites. The material of the ferrite was manganese zinc ferrite, and the model number was PC95. The size of each square ferrite was 105 mm x 105 mm x 5 mm. The square ferrites were directly bonded and connected with epoxy resin.

[Comparative Example 3]
As a comparative example of Example 1, the wireless charging magnetic shield structure is tiled by seven nanocrystalline strips obtained in step (1) in Example 1, i.e., no cutting and subsequent design and processing in step (2) is performed. The size of the multi-layer nanocrystalline strips is 60 mm x 420 mm x 3 mm. The nanocrystalline strips are bonded together by the colloid of the thermal conduction unit in Example 1.

The test results of Example 1 and Comparative Examples 1 to 3 are shown in Figure 3. As can be seen from the test results, when the thickness of the magnetic shield structure is the same, the special design according to the present application has advantages in terms of charging efficiency, weight reduction, and reliability. When the thickness of the ferrite magnetic body is increased to 5 mm, the efficiency is equivalent to that of the present application, but the differences in weight reduction and reliability become more obvious. The magnetic shield structure according to the present application showed a slight increase in temperature after charging for 30 minutes, but this did not have a significant impact on the safety of the entire system. Compared with the magnetic shield structure composed of tiled and joined nanocrystalline strips, the present application had clear advantages in terms of charging efficiency and temperature rise.

[Example 2]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conduction unit.

The nanocrystalline unit was composited with 120 layers _of nanocrystalline material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The _{nanocrystalline} material has a real permeability of 1634 in the operating mode with an operating frequency of 100 _kHz . The average thickness of the nanocrystalline material is 20 microns, and the thickness of the adhesive layer is 5 microns. The nanocrystalline unit is shaped like a rectangular parallelepiped, of which the surface shape is square, and the size of the side length a is 14 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 4.5:1. The size b, which is the distance between adjacent nanocrystal units, is 0.3 mm.

The magnetic shield structure consisting of the nanocrystal unit and the thermal conduction unit has a size h of 3 mm in the thickness direction.

test:
First, the permeability of the nanocrystalline strip was tested for subsequent calculations. The nanocrystalline strip was the nanocrystalline strip in step (1) above. The nanocrystalline strip was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm to perform the permeability test. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 4]
The comparative example for Example 2 is similar to Example 2 except that the real permeability of the nanocrystalline material is 567.

[Comparative Example 5]
The comparative example for Example 2 is similar to Example 2 except that the real permeability of the nanocrystalline material is 16,450.

The test results for Example 2, Comparative Example 4, and Comparative Example 5 are shown in Figure 4. As can be seen from the test results, after the magnetic permeability of the nanocrystalline material exceeded a certain range, the efficiency of the entire charging system decreased.

[Example 3]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conduction unit.

The nanocrystalline unit was composited with 120 layers _of nanocrystalline material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The _{nanocrystalline} material has a real permeability of 2153 in the operating mode at an operating frequency of 100 _kHz . The average thickness of the nanocrystalline material is 19 microns, and the thickness of the adhesive layer is 6 microns. The nanocrystalline unit is a rectangular parallelepiped in shape, of which the surface shape is a square, and the size of the side length a is 12 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 1.5:1. The size b, which is the distance between adjacent nanocrystal units, is 0.2 mm.

The magnetic shield structure consisting of the nanocrystal unit and the thermal conduction unit has a size h of 3 mm in the thickness direction.

test:
First, the permeability of the nanocrystal strip was tested for subsequent calculations. The nanocrystal strip was the nanocrystal strip in step (1) above. The nanocrystal was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm for the permeability test. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 6]
The comparative example of Example 3 is similar to Example 3, except that the thickness of the adhesive layer in nanocrystal unit 1 is 3 microns, the nanocrystal material is 136 layers, and the adhesive layer is 135 layers.

[Comparative Example 7]
The comparative example of Example 3 is similar to Example 3, except that the thickness of the adhesive layer in the nanocrystal unit is 14 microns, there are 92 layers of nanocrystal material, and there are 91 layers of adhesive layer.

The test results for Example 3, Comparative Example 6, and Comparative Example 7 are shown in Figure 5. As can be seen from the test results, when the thickness of the adhesive layer is too thin, the adhesion between the layers of nanocrystalline material is poor, and reliability is reduced. When the thickness of the adhesive layer is too thick, the magnetic isolation and shielding effect of the magnetic material is reduced, affecting the coupling coefficient of the entire system and reducing the charging efficiency of the wireless charging system.

[Example 4]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conduction unit.

The nanocrystalline unit was composited with 120 layers of _{nanocrystalline} material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The _{nanocrystalline} material has a real permeability of 3146 in the operating mode at an operating frequency of 100 kHz, the average thickness of the nanocrystalline _material is 20 microns, and the thickness of the adhesive layer is 5 microns. The nanocrystalline unit is shaped like a rectangular parallelepiped, of which the surface shape is square, and the size of the side length a is 11 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 2:1. The size b, which is the distance between adjacent nanocrystal units 1, is 0.1 mm.
The magnetic shield structure consisting of the nanocrystal unit and the heat conduction unit has a size h of 3 mm in the thickness direction.

test:
First, the permeability of the nanocrystal strip was tested for subsequent calculations. The nanocrystal strip was the nanocrystal strip in step (1) above. The nanocrystal was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm for the permeability test. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 8]
The comparative example of Example 4 is similar to Example 4 except that the side length a of the nanocrystal unit is 4 mm.

[Comparative Example 9]
The comparative example of Example 4 is similar to Example 4 except that the side length a of the nanocrystal unit is 16 mm.

The test results for Example 4, Comparative Example 8, and Comparative Example 9 are shown in Figure 6. As can be seen from the test results, when the value of a exceeds a certain range, the charging efficiency of the system is obviously reduced, and when the value of a is too large, excessive eddy current loss occurs, and the temperature rise is obvious.

[Example 5]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conduction unit.

The nanocrystalline unit was composited with 120 layers _of nanocrystalline material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The nanocrystalline material has a real permeability of ₁₄₃₇₁ in the operating mode with an operating frequency of 100 _kHz . The average thickness of the nanocrystalline material is 20 microns, and the thickness of the adhesive layer is 5 microns. The nanocrystalline unit is shaped like a rectangular parallelepiped, of which the surface shape is a square, and the size of the side length a is 6 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 3:1. The size b, which is the distance between adjacent nanocrystal units 1, is 0.2 mm.

The magnetic shield structure consisting of the nanocrystal unit and the thermal conduction unit has a size (h) of 3 mm in the thickness direction.

test:
First, the permeability of the nanocrystal strip was tested for subsequent calculations. The nanocrystal strip was the nanocrystal strip in step (1) above. The nanocrystal was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm for the permeability test. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 10]
The comparative example of Example 5 is similar to Example 5, except that only a thermally conductive potting agent is used in the thermally conductive unit, and no epoxy resin is used.

[Comparative Example 11]
The comparative example to Example 5 is similar to Example 5, except that only epoxy resin is used in the thermally conductive unit, and no thermally conductive potting material is used.

[Comparative Example 12]
The comparative example of Example 5 is the same as Example 5 except that the mass ratio of the thermally conductive potting material to the epoxy resin in the thermally conductive unit is 0.8:1.

[Comparative Example 13]
The comparative example of Example 5 is the same as Example 5 except that the mass ratio of the thermally conductive potting material to the epoxy resin in the thermally conductive unit is 6:1.

The test results for Example 5 and Comparative Examples 10 to 13 are shown in Figure 7. As can be seen from the test results, when no epoxy resin is added to the thermal conductive unit or when its content is low, the colloid adhesion is poor and reliability is low. When no thermal conductive potting agent is added to the thermal conductive unit or its content is low, the heat dissipation characteristics of the thermal conductive unit are poor, which further affects the charging efficiency.

[Example 6]
The magnetic shield structure mainly includes a nanocrystal unit and a heat conduction unit.

The nanocrystalline unit was composited with 120 layers of nanocrystalline material and ₁₁₉ layers of adhesive layer. The composition of the nanocrystalline material is _{Fe73.5Si13.5Nb3B9Cu1} . The _{nanocrystalline} material has a real permeability of 5314 in the operating mode of an operating frequency of 100 _kHz . The average thickness of the nanocrystalline material is 20 _microns , and the thickness of the adhesive layer is 5 microns. The nanocrystalline unit is shaped like a rectangular parallelepiped, of which the surface shape is a square, and the size of the side length a is 10 mm.

The thermally conductive unit is a mixture of a thermally conductive potting agent and an epoxy resin. The thermally conductive potting agent is a two-component silica gel material. The epoxy resin is an epoxy resin modified with a polyamide resin. The mass ratio of the thermally conductive potting agent to the epoxy resin is 4.5:1. The size b, which is the distance between adjacent nanocrystal units, is 0.3 mm.

The magnetic shield structure consisting of the nanocrystal unit and the thermal conduction unit has a size h of 3 mm in the thickness direction.

test:
First, the permeability of the nanocrystal strip was tested for subsequent calculations. The nanocrystal strip was the nanocrystal strip in step (1) above. The nanocrystal was punched into a circular loop with an outer diameter of 18.8 mm and an inner diameter of 9.9 mm for the permeability test. The test equipment was a Toku E4990A, and the test frequency was 100 kHz.

Tests were conducted on the wireless charging efficiency and temperature rise of the magnetic shield structure according to the present application. The magnetic shield structure was placed in a high-power wireless charging system, and the charging efficiency was measured after the wireless charging system had been operating for 30 minutes. The surface temperature of the magnetic shield structure was measured with a temperature measuring device, and the maximum temperatures on the surface of the magnetic shield structure before charging and after 30 minutes of operation were recorded, and the temperature rise before and after charging was calculated, and the power of the wireless charging system was 11 kW. The magnetic shield structure was weighed on a balance, and an initial reliability test was conducted on the magnetic shield structure. Reliability includes impact resistance properties, adhesion properties between nanocrystal units, etc.

[Comparative Example 14]
The comparative example of Example 6 is the same as Example 6 except that the distance between adjacent nanocrystal units is 0.08 mm.

[Comparative Example 15]
The comparative example of Example 6 is the same as Example 6 except that the distance between adjacent nanocrystal units is 0.6 mm.

The test results for Example 6, Comparative Example 14, and Comparative Example 15 are shown in Figure 8. As can be seen from the test results, if b is too small, the thermally conductive colloid cannot completely fill the gaps between the nanocrystals, resulting in poor system reliability, and if the value of b is too large, the magnetic isolation and shielding effect of the entire magnetic shield structure is significantly reduced, the coupling coefficient of the charging system is reduced, and the charging efficiency is further deteriorated.

Of course, the above examples of the present application are merely illustrative to clearly explain the present application, and do not limit the embodiments of the present application. Those skilled in the art can make various obvious changes, readjustments and substitutions without departing from the scope of protection of the present application. There is no need or method to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of the claims of the present application.

Claims (9)

A magnetic shield structure for wireless charging, comprising a plurality of nanocrystal units and a heat conduction unit,
the thermal conduction units are provided between the nanocrystal units and are used for connecting the nanocrystal units and for thermal conduction;
The nanocrystalline unit comprises multiple layers of nanocrystalline material.
Magnetic shielding structure for wireless charging. The material of the thermally conductive unit includes a thermally conductive potting agent and an epoxy resin.
The magnetic shield structure for wireless charging according to claim 1. The thermal conductive potting agent is made of silica gel material;
The epoxy resin is modified with a polyamide resin.
The magnetic shield structure for wireless charging according to claim 2. The mass ratio of the thermally conductive potting agent to the epoxy resin is 1:1 to 5:1;
The magnetic shield structure for wireless charging according to claim 3. The layers of nanocrystalline material are bonded together by an adhesive layer.
The magnetic shield structure for wireless charging according to claim 1. the nanocrystal units are rectangular;
the plurality of nanocrystal units are in a matrix distribution;
The formed magnetic shield structure is rectangular.
The magnetic shield structure for wireless charging according to claim 1. The nanocrystal unit has a side length of 5 to 15 mm and a thickness of 1 to 10 mm;
The magnetic shield structure for wireless charging according to claim 6. The nanocrystal units have a thickness of the nanocrystal material of each layer of 14 to 20 microns, and the distance between adjacent nanocrystal units is 0.1 to 0.5 mm.
The magnetic shield structure for wireless charging according to claim 1. A manufacturing method used for the magnetic shield structure for wireless charging according to any one of claims 1 to 8, comprising the steps of:
(1) the nanocrystal strip is sequentially double-sided-film-applied and split, and then multiple layers of the nanocrystal strip are adhered and laminated through adhesive layers to reach a desired thickness h;
(2) cutting the composite material of the multiple layers of nanocrystal strips and adhesive layer produced in step (1) into multiple rectangular nanocrystal units with square top faces;
A step (3) of arranging and fixing the plurality of nanocrystal units produced in the step (2) on a mold or a flat plate so that the distance between adjacent nanocrystal units is b;
(4) mixing and stirring the thermally conductive potting agent and the epoxy resin according to the ratio to obtain a colloid for forming a thermally conductive unit;
Step (5) of filling the gaps between the nanocrystal units in step (3) with the colloids of the heat conduction units produced in step (4) to form a semi-finished magnetic shield structure;
and (6) hardening the magnetic shield structure semi-finished product manufactured in step (5) to obtain a magnetic shield structure finished product.
Production method.